BOVOVACCINE 357 



transitory accidents. Very often the reaction is doubtful. In cattle, 

 doubtful cases, owing to the difficulty of examination, must be 

 regarded as negative. In these animals a simple (primary) ophthalmo- 

 reaction is a very unreliable procedure and cannot take the place of 

 inoculation with tuberculin. A secondary ophthalmo-reaction gives 

 very much more trustworthy results/' White and McCampbell, 

 reporting on the same subject to the same Congress, however, place 

 more confidence in the primary test, but they likewise do not consider 

 it of much value in the diagnosis of tuberculosis in cattle. In some 

 cases the reaction is very slight, in others pronounced congestion 

 with profuse exudates is noted. They were inclined to rely primarily 

 on the result of the first instillation of tuberculin. In the majority 

 of animals tested the reaction increases in its intensity with each 

 subsequent instillation of tuberculin. This fact indicates the develop- 

 ment of a local hypersusceptibility, or anaphylaxis, associated with a 

 partial immunity. 



Pirquet's Cutaneous Tuberculin Test. This consists in the vaccination 

 with a few drops of tuberculin on the arm, and has been extensively 

 used in children but very little in animals. The same is true of the 

 so-called dermo-reaction, where a tuberculin-lanolin ointment is rubbed 

 into the skin. These two methods, like the ophthalmo-tuberculin 

 test, are of no great value in the detection of latent tuberculosis in 

 domestic animals. 



IMMUNIZATION AND PROTECTIVE INOCULATION. 



Bovovaccine. Starting from the viewpoint that the bacillus of 

 human tuberculosis, derived from the sputum of tubercular patients, 

 is not very virulent for cattle, von Behring has worked out a method 

 of protective and immunizing inoculation. Since tubercle bacilli 

 of human derivation, even apart from those comparatively not 

 numerous cases of infection by bacilli of the bovine type, vary a good 

 deal in their effect upon cattle, it is not a matter of indifference 

 what stem of human tubercle bacilli is selected for the preparation 

 of a vaccine to be used on bovines. Von Behring, after many pre- 

 liminary experiments, selected a culture of a low degree of virulency 

 for cattle which had never led to any untoward accidents. From 

 transplants of this original and extensively tested culture all his 

 bovovaccine has been prepared. The experience of von Behring and 

 his co-workers and of those who have tried his method and vaccine, 

 like Hutyra, a French commission and others, has been very favorable 

 both as to the harmlessness of the procedure and as to the protection 

 which it affords against natural infection or artificial inoculation 

 with the bovine tubercle bacillus. The bovovaccine is prepared from 

 a four to six-weeks-old glycerin bouillon culture of the selected human 

 tubercle bacillus. The culture is filtered and the bacilli remaining 

 on the filter are dried in vacuo over sulphuric acid for twenty-four 



